Anyone pumped for this week's launch of Google's Home Hub might want to temper their excitement. A smart home is a surveilled home. That's been the concern of privacy activists since citizens started lighting up their abodes with so-called "smart" tech in recent years.

Take Google's current smart home division, Nest Labs. It's been told to hand over data on 300 separate occasions since 2015. That's according to a little-documented transparency report from Nest, launched a year after the $3.2 billion Google acquisition. The report shows around 60 requests for data were received by Google's unit in the first half of this year alone. In all those cases recorded from 2015 onwards, governments have sought data on as many as 525 different Nest account holders.

The Nest transparency report isn't as detailed as its parent company's, or those of other tech giants like Facebook, Microsoft and Twitter. It doesn't give specific numbers on data requests, for instance, only a bar chart where the user is left to guess at precise figures. It also doesn't drill down what countries made what requests. Nest didn't respond to requests for more specific data.

It's clear Nest does hand over information in many cases where it's asked, but in most it doesn't. In the first half of 2018, less than 20% of requests received data in return. That's the lowest proportion of any half year since the Google subsidiary started recording information. Back in the second half of 2015, the proportion was up at nearly 60%.

"If a US government agency presented us with a search warrant to investigate a crime they think was captured on a Nest Cam, we wouldn't just hand over user data," Nest says on its transparency report page. "We'd analyze the request to be sure the warrant wasn't overly broad, then we'd make sure the information they requested was within the scope of the warrant."